The present invention relates to a method of transmitting information between at least two units consisting of two computer stations or two personalised portable objects or one personalised portable object and one computer station. The portable object is a personalised watch, for example. For implementing the method, the portable object, for example the watch, and the computer station each comprise means for transmitting and/or receiving signals which are activated alternately in a transmitting mode and a receiving mode. The signals transmitted, which are preferably short-range radio-frequency signals, include at least one information frame modulated onto a carrier chosen from a plurality of available carriers in the computer station and/or in the watch. The information in the frame relates, for example, to data to be stored in a memory of the watch or to data to be transmitted from the memory to the computer station. The information can also concern commands to execute operations or requests to identify the transmitting source.
The data from the memory or the data to be stored in the memory is preferably data of a diary function. When the diary function is active, it is possible to consult data records previously stored by activating keys of the watch in various menus. The various menus of the diary function relate to notes, an address book, a diary, transmission of data by radio-frequency signals and parameters. One menu of the diary function concerns a data transmission mode. In the selected transmission mode, data from the memory of the watch is transmitted to the computer station or data is received from the computer station. When this menu is selected, it is in principle no longer possible to use other diary functions of the watch until the transmission phase has terminated.
The transfer of data between a computer station and an electronic watch by means of short-range radio-frequency signals is already known in the art. For example, European Patent Application EP 0 957 589 in the name of the Applicant describes a communication system linking first and second units. The units each include means for transmitting and/or receiving short-range radio-frequency signals for bi-directional transmission of data. The first unit is preferably a personalised electronic watch and the second unit is a computer station. The electronic watch with its means for transmitting and/or receiving signals must be within a particular coverage area of the computer station for data to be exchanged.
Once communication has been established from the computer station, the transmitting and/or receiving means of the watch must be active at least during each period of transmitting and/or receiving radio-frequency signals.
The data transferred is preferably data of a diary function. The data is transferred in the form of packets of information each contained in an information frame modulated onto a high-frequency carrier. The size of each packet transmitted depends on the size of a non-volatile memory page in the watch. A plurality of information frames must therefore be transmitted to transfer all of the information.
In the above patent application, a plurality of computer stations can each communicate with a respective personalised watch in the same coverage area. To this end, the transmission of data signals between each station and a respective personalised watch uses a high-frequency carrier different from the carriers for transmission between the other stations and the other personalised watches. The carrier onto which the data signals are modulated is chosen in the computer station, for example, as a function of an anti-collision protocol that is well-known in the art, so as not to interfere with the transmission of data signals between other stations and other watches.
In the application EP 0 957 589, there is no provision for limiting the power consumption of the watch during bidirectional transmission of diary function data, which is a major drawback. As the electronic watch is a small instrument supplied with power by a low-power source of energy, it is necessary to optimise the transmission time of all the necessary data between the computer station and the watch. This optimisation must limit the time of operation of the transmitting and/or receiving means of the watch, which consume a large amount of energy.